1. Field of the Invention
The present invention relates to a scale system for use with a movable table and, in particular, to measure the position of a rip fence on a table saw having a movable auxiliary table portion.
2. Scope of the Prior Art
Tables that are used for various purposes are often provided with an auxiliary table that moves relative the stationary main table. In certain applications, scale systems are used to position the movable table a specific distance from a point designated on the stationary table. In addition, separate units can be used with the table where the unit is movable relative the table. Similarly, scale systems are used to position the movable unit at a specific position relative the designated point.
Table saws that have a movable rip fence often use a scale system to position a movable auxiliary table or rip fence. Table saws of various designs include a base and an upper cutting surface having an opening through which a blade extends. The upper surface supports a material, such as wood, as it is pushed toward the blade for cutting. Table saws have traditionally been stand-alone pieces of equipment that are used in workshops. Because most stand-alone table saws are used in large open spaces, the dimensions of the table saw can be large enough to support materials of various sizes for cutting.
Tables saws that are used in workshops are not readily moved from one location to another. At construction sites, it is useful to have a table saw that can be easily moved from one location to another or between different construction sites. Accordingly, smaller and portable table saws have been designed. These table saws use lighter materials and have reduced the dimensions of the base and the upper surface to reduce the size and weight of the table saw thereby creating the desired portable table saw. Portable table saws can be designed with movable auxiliary table sections to increase the working space of the table saw while maintaining a saw that is portable. The portable table saws also use a separable folding table, or saw stand, to hold the table saw at the correct height for operation.
An integral part of most table saws is a movable rip fence. The rip fence is positioned perpendicular to the upper cutting surface and is aligned generally parallel to the position of the blade. Most rip fences are designed to span between the front edge and the rear edge of the upper cutting surface. Moreover, the rip fence can be positioned in any position along the upper surface and is secured in such a position by a locking mechanism. The rip fence is usually secured in a position a given distance away from the blade and can be put on either side of the blade. For table saws that include auxiliary tables, the rip fence can slide over the entire span of the table. When the rip fence is secured in a position, the material can be pushed against the side of the rip fence and along the upper surface while it is being cut by the blade. Thus, accurate and straight cuts can be made.
Table saws have long used different types of scale systems to determine the location of the rip fence relative the blade. The general purpose of those scale systems is for the user to know the size of the piece of wood being cut. For example, if the cut piece of wood is to be 10 inches, the user uses the scale system to position the rip fence 10 inches from the blade. The rip fence is secured in that position by the rip fence""s locking mechanism. The side of the wood is pushed against the rip fence, and the user slides the wood across the upper cutting surface and along the rip fence to make a parallel cut by the blade.
The most common scale system used for cutting wood has a measurement scale placed on the front fence support rail attached to the upper surface of the table saw. The measurement scale can extend in two directions so that the position of the rip fence can be placed on either the right or left side of the blade. The rip fence is provided with a pointer to measure the distance from the blade on the measurement scale. The zero marking of the measurement scale is placed on the front fence support rail where the pointer is positioned when the rip fence is immediately adjacent the blade. The zero marking is therefore aligned relative the blade but not necessarily in the position on the scale aligned with the blade. The last marking on each side of the blade is placed so that the pointer on the rip fence can read the distance from the blade when the rip fence is in its furthest, supported position.
Most rip fences are designed to slide on rails attached to the front and rear edges of the table saw. Accordingly, the scale system can be positioned on those rails. For those embodiments, the pointer is placed in a viewing window on the rip fence. Alternatively, the scale system can be provided directly on the upper cutting surface. For that embodiment, the rip fence includes a pointer that extends from the rip fence to the scale on the upper cutting surface. The risk is that the pointer may be inadvertently adjusted thereby offsetting the calibration of the scale system.
Other rip fences are provided with dual use scale systems. These scale systems use at least two coinciding measurement scales where one measurement scale runs parallel to the second measurement scale. Dual scale systems are used for table saws where rip fences can be move on different rails for short or wide cuts. They can also be used for table saws where the cutting blade can be positioned at different locations on the upper cutting surface or when the table saw has a circular saw component and a router component. Other saws include a first measurement scale on one location of the saw and a second measurement scale at a different location of the scale. The first measurement scale can be used to position the rip fence and the blade and the second measurement scale can be used to measure the size of the wood.
Dual scale systems are also used with table saws where the rip fence can move into an extended position. For this type of table saw, the same measurement scale is used where each indication marking has multiple corresponding numbers. One set of numbers is used when the rip fence slides in the normal position. The second measurement scale of numbers is used when the rip fence is in the extended position. The distance of offsetting the numbers exactly corresponds to the distance between the rip fence in the normal position and the extended position. Accordingly, the same indication markings can be used.
In view of the foregoing, it is an object of the present invention to have a scale system for use with a table saw that simply determines the position of a movable rip fence relative the blade.
It is also an object of the present invention to provide a scale system for a table saw that has a movable auxiliary table where the rip fence moves relative the stationary table and with the auxiliary table. To operate with the auxiliary table, the scale system requires multiple indication markings for use with the stationary table and the auxiliary table. It is also an object of the present invention to include multiple pointers that operates with the multiple measurement scales. In addition, the scale system can include a third measurement scale so that the rip fence can be used on two sides of the blade.
The present invention relates to a table saw that includes a scale system to determine the location of a rip fence that is slidable relative to the table saw. The table saw used with the scale system includes a base portion and upper cutting surface. A blade extends through an opening in the upper surface to cut wood or other material. The upper surface is used to support the material as it is pushed on the table saw and cut by the blade. Front and rear edge surfaces extend perpendicularly from the front and rear edges of the upper surface. A rip fence is also provided that slides along the upper cutting surface and can be locked in any position so that it is parallel to the blade.
The rip fence of the present invention can be used with a table saw that has a movable auxiliary table. The auxiliary table can move between a first position adjacent the upper surface and a second position separated from the upper surface according to any of the many known methods. In the present invention, the auxiliary table is connected to rails that slide on brackets attached to the front and rear edge surfaces of the upper cutting surface.
The rip fence moves between positions relative the upper surface and auxiliary table and can be locked in any position such that the rip fence is parallel to the blade. This arrangement ensures that accurate cuts are made of material. The rip fence slides within a slot formed in the front rail so that the rip fence moves relative the upper surface. The front rail is movably attached to the upper cutting surface.
The rip fence includes a locking mechanism to secure the rip fence in a position along the rails attached to the upper cutting surface or the auxiliary table surface. In the locked position, wood can be pressed against the locked rip fence and cut by the blade as the wood is pushed across the upper cutting surface. In the released position, the rip fence can slide between a position adjacent the blade and an extended position at the ends of the table. When a desired position is located, the rip fence is put in the locked position to secure it for operation of the saw.
The scale system of the present invention is used to position the rip fence on the upper cutting surface or the auxiliary table a given distance from the blade. The given distance is the desired width or length of the wood being cut. The scale system is designed so that the rip fence can be positioned on either side of the blade and the desired measured distance from the blade can be found. On the side of the table saw corresponding to the auxiliary table, the present invention includes dual scale having a first and second measurement scales of indication markings. The scale system is positioned proximate the front edge of the stationary table. The scale system can also be located on the rails on which the auxiliary table slide and be movable with the rails.
The first measurement scale of indication markings is used when the auxiliary table is in the first position adjacent the stationary table and when the fence slides along the stationary and auxiliary tables. The zero marking of the first measurement scale of indication markings corresponds to the rip fence being adjacent the blade, or a zero distance, from the blade. The first measurement scale of indication markings extends to a last marking where the rip fence is in an extended position over the auxiliary table. A second measurement scale of indication markings is used when the rip fence is in the extended position on the auxiliary table and the auxiliary table moves between the first position adjacent the stationary table and the second position separated from the stationary table. The initial marking of the second measurement scale of indication markings has the same measurement as the last marking on the first measurement scale of indication markings. The measurement scale of the second measurement scale of indication markings increase in a counter, or opposing, direction to the markings of the first measurement scale. The final marking of the second measurement scale of indication markings indicates the distance from the blade when the rip fence is in the extended position over the auxiliary table and the auxiliary table is in the second position fully separated from the stationary table. In the preferred embodiment, a third set of indication markings is positioned proximate the dual scale system, but on the opposing side of the blade. The zero marking of the third set is located where the rip fence is immediately adjacent the left side of the blade. The third set is used when the rip fence slides to the left of the blade.
The scale system of the present invention includes two separate pointers to read the first, second and third measurement scales. The first pointer is placed on the rip fence. Accordingly, the first pointer is used to read the measurement markings on the first and third measurement scale as the rip fence slides along the rails movably attached to the stationary table. The second pointer is placed on the upper cutting surface of the stationary table. The second pointer is used to read the measurement markings on the second measurement scale when the rip fence moves with the rails attached to the auxiliary table as the auxiliary table and rails move between the first and second positions.